In recent years, pattern formation using resist has been employed in order to manufacture various devices. In particular, imprinting method takes advantages of easy repetitive molding of fine structures including nano-structure, and of less emission of hazardous waste or discharge, and is expected to be applied to various fields.
The imprinting method includes two technologies, which are thermal imprinting using thermoplastic resin as a workpiece, and photo-imprinting using curable composition for imprints. In the thermal imprinting, a mold is pressed against a polymer resin heated at or above the glass transition temperature, and is then released after cooled, to thereby transfer a fine structure onto the resin on a substrate. The method is applicable to a variety of resin materials and also to glass materials, and is expected to be applied to various fields.
On the other hand, in the photo-imprint method where a photo-curable composition is cured by photo irradiation through a transparent mold or a transparent substrate, the transferring material does not require heating in pressing it against the mold, and therefore the method enables room-temperature imprinting. Recently, new developments having the advantages of the above two as combined, have been reported, including a nanocasting method and a reversal imprint method for forming three-dimensional structures.
For the nanoimprint methods as above, proposed are applied technologies mentioned below.
In the first technology, the molded pattern itself has a function, and is applied to various elements in nanotechnology and to structural members. Its examples include various micro/nano. optical elements and high-density recording media, as well as structural members in optical films, flat panel displays, etc.
The second technology is for hybrid-molding of microstructures and nanostructures, or for construction of laminate structures through simple interlayer positioning, and this is applied to production of .mu.-TAS (micro-total analysis system) and biochips.
In the third technology, the formed pattern is used as a mask and is applied to a method of processing a substrate through etching or the like.
In these technologies, high-precision positioning is combined with high-density integration; and in place of conventional lithography technology, these technologies are being applied to production of high-density semiconductor integrated circuits and transistors in liquid-crystal displays, and-also to magnetic processing for next-generation hard discs referred to as patterned media. Recently, the action on industrialization of the above-mentioned nanoimprint technologies and their applied technologies has become active for practical use thereof.
As activities regarding the photonanoimprint method-have increased, an issue of adhesiveness between a substrate and a curable composition for imprints has been gaining more attention. In more details, the curable composition for imprints is generally applied to the surface of the substrate to form a layer, and is cured by photoirradiation while being kept under a mold, but the curable composition for imprints may adhere onto the mold when the mold is separated thereafter. Poor separability of the mold may degrade formability of the resultant patterns. This is ascribable to apart of the curable composition for imprints remaining on the mold.
There has therefore been a need to enhance adhesiveness between the substrate and the curable composition for imprints. Known methods of enhancing the adhesiveness between the substrate and the curable composition for imprints are described in Patent Literature 1 and Patent Literature 2. More specifically, according to Patent Literature 1, a polymerizable monomer having a group capable of interacting with the substrate is used to enhance the adhesiveness between the substrate and the curable composition for imprints. According to Patent Literature 2, an aromatic polymer is used to enhance the adhesiveness between the substrate and the curable composition for imprints.